Modular optical particle counter sensor and apparatus

Abstract

A modular optical particle counter sensor and apparatus are described that consolidates counting functionality on a single main counter board and has expandable functionality through connections to plug-in system boards. The modular optical particle sensor may be directly connected to a manifold with an integrated Venturi for better controlling the flow rate of the air stream passing through the apparatus for sampling.

We claim: 
     
       1. A compact optical particle counter comprising:
 a housing that contains a controller, a light source, a light detector, and a flow channel manifold to move a particle flow through a beam of light, wherein the flow channel manifold includes a Venturi used with a flow actuator to control a flow rate of the particle flow, wherein the controller is connected to a memory and a communication port connected to a communication network, and wherein the controller operates a communication interface that transmits operational state data for the optical particle counter regarding an operational mode to an external computing device; 
 a signal processing circuit to process detected signals above a threshold for at least one output channel, an analog to digital converter that converts analog signals above the threshold to digital signals to generate particle count data; 
 and 
 a core module circuit board assembly on which the signal processing circuit and the controller are mounted, the core module circuit board assembly further comprising at least one connector to electrically connect the controller to an attachable circuit board, wherein the attachable circuit board is an option board configured to control at least one of a power level and a sampling parameter of the optical particle counter. 
 
     
     
       2. The particle counter of  claim 1  wherein the manifold further comprises an output for the Venturi that is connected to an input to a sensor chamber wherein the light beam traverses the sensor chamber and the flow actuator comprises a pump, the manifold further including a connector that directly connects the Venturi to a filter at a pump entry and a flow sensor. 
     
     
       3. The particle counter of  claim 1  wherein the signal processing circuit further comprises:
 a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC) connected to the controller such that the FPGA or ASIC controls setting of pulse thresholds for an analog front end signal processing circuit. 
 
     
     
       4. The particle counter of  claim 1  wherein the signal processing circuit further comprises a field programmable gate array (FPGA) connected to the controller such that the FPGA controls setting of pulse thresholds with one or more pulse width modulators (PWM). 
     
     
       5. The particle counter of  claim 1  wherein an FPGA is mounted to the core module circuit board on which the controller, an analog front end circuit, an analog to digital converter and a power control circuit are mounted. 
     
     
       6. The particle counter of  claim 5  wherein the FPGA includes a plurality of registers including a user register for a user to configure the particle counter for a particle counting operation. 
     
     
       7. The particle counter of  claim 6  wherein the plurality of registers includes one or more of a sampling register to start and/or stop a sampling operation of an airflow through an airflow path within the housing, a calibration register to calibrate the particle counter, a configuration register to configure one or more circuit configurations of the particle counter, and/or a diagnostic register to monitor the particle counter or diagnose a condition of the particle counter. 
     
     
       8. The particle counter of  claim 1  wherein the attachable circuit board comprises a display and a battery mounted in the housing. 
     
     
       9. The particle counter of  claim 1  wherein the attachable circuit board comprises a universal serial bus (USB) connection. 
     
     
       10. The particle counter of  claim 1  wherein the attachable circuit board comprises an environmental sensor. 
     
     
       11. The particle counter of  claim 1  wherein the attachable circuit board further comprises an Ethernet connector. 
     
     
       12. The particle counter of  claim 1  wherein the attachable circuit board comprises a power over Ethernet connector. 
     
     
       13. The particle counter of  claim 1  wherein the attachable circuit board further comprises a touchscreen display, a power supply and a display controller. 
     
     
       14. The particle counter of  claim 1  wherein the attachable circuit board further comprises a wireless transceiver. 
     
     
       15. The particle counter of  claim 1  further comprising a light source circuit board on which the light source is mounted with a light detector and a light source controller and a real time clock calendar connected to the controller. 
     
     
       16. The particle counter of  claim 1  wherein the housing has a volume of less than 2000 cubic centimeters such that the particle counter has a weight of less than 460 grams. 
     
     
       17. The particle counter of  claim 1  wherein the particle counter has a weight of less than 910 grams. 
     
     
       18. A method of operating a particle counter comprising:
 connecting a circuit module to a connector on an optical particle counter base unit, the optical particle counter base unit including an airflow inlet, an airflow outlet and an airflow path through a housing including a Venturi, and a controller that controls a pulse threshold circuit to process analog signals received from a light detector, the controller being connected to a light source controller for a light source that emits light through the airflow path, wherein the Venturi is used with a flow actuator to control a flow rate of airflow in the airflow path; and 
 communicating with an external device with at least one of a plurality of communication channels connected to the controller, the controller being connected to the circuit module to control a circuit module operation. 
 
     
     
       19. The method of  claim 18 , further comprising:
 selecting the circuit module from a plurality of circuit modules that are connectable to the connector wherein the base unit includes a field programmable gate array (FPGA) or application specific integrated circuit (ASIC) connected to the controller. 
 
     
     
       20. The method of  claim 18 , further comprising:
 using a pump in the base unit to control air flow through the housing. 
 
     
     
       21. The method of  claim 18 , further comprising:
 selecting a switch in the base unit to select between communication interfaces. 
 
     
     
       22. The method of  claim 21  wherein the communication interface selectable by the switch is one of an isolated RS-485 interface, UART interface or controls a Modbus used to control and monitor the particle counter, wherein the Modbus is a Modbus RTU or Modbus ASCII. 
     
     
       23. The method of  claim 18  further comprising an analog front end connected to the detector and an analog to digital converter and wherein particle counting is implemented on the controller and a flow sensor connected to the controller senses a particle flow to provide closed loop pump control of an airflow rate through the manifold. 
     
     
       24. The method of  claim 18  wherein the particle counter includes one, two, three or four particle channels, has a volume of less than 2000 cubic cm and a weight of less than 910 grams. 
     
     
       25. The method of  claim 24  wherein a particle size range of the particle channels is fixed during particle operation and is changeable only during calibration. 
     
     
       26. The method of  claim 18 , further comprising:
 communicating with an external system that provides data storage. 
 
     
     
       27. The method of  claim 18  further comprising programming the particle counter to control particle counting operations with an internal clock and controlling operations of the particle counter with a clock calendar mounted on a printed circuit board with the controller and an analog front end circuit that applies thresholds to detected signals from the light detector. 
     
     
       28. The method of  claim 18 , further comprising:
 configuring a server to transmit a plurality of operating parameters to the optical particle counter. 
 
     
     
       29. The method of  claim 18 , further comprising:
 configuring an external computing device to select an alarm indicator state for each of a plurality of operational states of the device.